1. Field
The present disclosure relates to a hybrid integrated module that includes a semiconductor die mechanically coupled to an integrated device in which the substrate has been removed, and in which an optical device is disposed on a back surface of the integrated device.
2. Related Art
Silicon-on-insulator (SOI) technology is often used to implement integrated optical components. In particular, optical components, such as an optical waveguide, can be fabricated in a silicon layer of an SOI wafer, which is separated from a silicon substrate by a silicon-dioxide layer (which is sometimes referred to as a ‘buried-oxide’ or BOX layer). In order to reduce optical losses in the silicon substrate, typically the thickness of the BOX layer is selected so that an optical signal is completely confined in an optical component in the silicon layer (i.e., an optical mode associated with the optical signal does not extend through the BOX layer).
In principle, SOI wafers also allow electronic circuits to be integrated with the optical components on a common chip. In practice, the design parameters for electronic circuits are often different than those for the optical components. For example, in photonic applications the silicon layer usually has a thickness of 0.2-0.3 μm, and the BOX layer usually has a thickness greater than 0.5 μm. In contrast, in many electronic applications (such as a processor, digital logic, a radio-frequency circuit, memory, etc.) the BOX layer has a thickness as low as 0.1 μm. This thicknesses results in significant evanescent coupling of the optical signal to the silicon substrate, with a commensurate increase in the optical losses due to absorption and scattering in the silicon substrate.
Hence, what is needed is an integrated module that can accommodate optical components and electrical circuits without the above-described problems.